Don't suppress build error backtraces

[jtrost]

Which operating system and version is the project developed on?
OS X 10.12.3

Which version of ruby is the project developed on?
2.4.0

Which version of npm is the project developed on?
4.1.2

Which version of ember-cli is the project developed on?
2.11.0

What is the rails version?
5.0.1

What is the ember-cli-rails version (from Gemfile)?
0.8.4

What is the ember-cli-rails-addon version (from package.json)?
0.8.0

I received this error in my application.

ActionView::Template::Error (:frontend has failed to build: 
):

It contained no backtrace, so I did not know what was wrong. I opened /lib/ember_cli/build_monitor.rb and inspected build_errors, and got this:

["\e[31m\n", "\e[31mMissing npm packages: \e[31m\n", "\e[0mPackage: \e[0m\e[36member-changeset\e[31m\n", "\e[90m  * Specified: \e[31m\e[0m1.2.1\e[0m\n", "\e[90m  * Installed: \e[31m\e[0m(not installed)\e[0m\n", "\e[0mPackage: \e[0m\e[36member-changeset-validations\e[31m\n", "\e[90m  * Specified: \e[31m\e[0m1.2.4\e[0m\n", "\e[90m  * Installed: \e[31m\e[0m(not installed)\e[0m\n", "\e[31mRun `npm install` to install missing dependencies.\e[31m\n", "\e[39m\n"]

This line suppresses all but the first build error, which in my case is:

"\e[31m\n"

That is why I did not see a backtrace with my build error. But I now know that I need to run npm install. This gem should show the entire backtrace, and not just the first line.

[shcherbanikolay]

Maybe it will be help for somebody. When i got
ActionView::Template::Error (:frontend has failed to build: )
This seemed that it was all good with your rails project, but there were issues with ember part of it.
So i changed directory to my frontend project directory. Then runed ember server. And ember told me that i have missing npm packages. I run npm install, and it solved my issue. Excuse me for my bad English.

[tricknotes]

Fixed by #678, which is now on main.

BuildMonitor no longer reports build_errors.first — it joins every line of the failure that survives filtering, so the whole message reaches EmberCli::BuildError.

Replaying the exact build_errors array from this report against main (6b070cb) now produces:

:frontend has failed to build: 
Missing npm packages: 
Package: ember-changeset
  * Specified: 1.2.1
  * Installed: (not installed)
Package: ember-changeset-validations
  * Specified: 1.2.4
  * Installed: (not installed)
Run `npm install` to install missing dependencies.

instead of the bare :frontend has failed to build: that the leading \e[31m\n line used to produce.

Two notes:

• JavaScript stack frames ( at ...), DEPRECATION: warnings and Building notices are still filtered out, so what you get is the build tool's error report rather than a full JS backtrace. In the case reported here that is exactly the part that was missing.
• This covers the ember build --watch path that BuildMonitor monitors, which is the classic (non-Vite) blueprint — the setup in this report. A Vite-based application builds through Shell#compile, where a failure is raised by Runner#run! and the build tool's output goes straight to standard error.

The change is unreleased; it will ship in the next release after 0.14.0.

---

Generated by Claude Code